<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        
        html {
            font-size: 20px;
        }
        
        .box {
            /* rem是一个相对的单位  相对于根元素的字体大小 */
            width: 10rem;
            height: 10rem;
            background-color: #ff3040;
            display: flex;
            /* flex-direction: column;
            justify-content: space-around;
            flex-wrap: wrap;
            align-items: center;
            align-content: space-around;
            flex-flow: column wrap;
            flex: 1;
            flex-grow: ;
            flex-shrink: ;
            flex-basis: ;
            align-self: center;
            order: 1; */
        }
    </style>
</head>

<body>
    <div class="box"></div>
</body>

</html>